I was wondering if that would cause a backfire with it leaking on the pass side where all the pipes come together. It is leaking in the middle. I hooked up my buddys evap smoke machine and fixed all of the leaks in the system except for htis one due to it's location. The car still backfires and I guess it is due to this. How can I fix it? is there a way to do it on the car? does it need to be welded? thanks

 

A leak in the middle of the collector? That has to be welded if it's a hole.

 

Would this cause it to back fire on decel? how big of aleak does it need to be to cause a back fire? thanks